The present invention relates to a dielectric constant measuring apparatus detecting the dependence of the dielectric property of a sample on temperature, time, or frequency and, more particularly, to an improvement in the accuracy of data obtained by such measurement.
One conventional technique of this kind consists in applying a sinusoidal wave voltage of a given amplitude dependent on the dielectric constant of a sample, detecting the current induced in the sample at this time, and determining the complex dielectric constant from the correlation between the sinusoidal wave voltage and the current.
In the above-described prior art technique, the voltage of constant amplitude is applied without considering variations in the dielectric constant of the sample during measurement. Therefore, if the dielectric constant of the sample rises, the current increases. As a result, the dynamic range of the current detector is exceeded. If the dielectric constant drops, the current decreases. Then, the voltage signal from the current detector attenuates. This deteriorates the accuracy of reading of the peak value-measuring circuit and of the A/D converter. In either case, the measuring accuracy is deteriorated.